Skin cancer can look like a shiny bump, a scaly patch, a dark streak under a nail, or a sore that won’t heal. There’s no single appearance, because the three main types of skin cancer each show up differently on the body. Any new or changing spot that persists for more than two weeks is worth getting checked.
Basal Cell Carcinoma
Basal cell carcinoma is the most common skin cancer, and it often looks deceptively harmless. On lighter skin, the classic sign is a firm, raised, round growth with a shiny or pearly surface, usually pink or red. It can also appear as a flat, waxy, or scar-like patch that seems slightly different from the surrounding skin.
One telltale feature is a dip or indentation in the center of the growth, almost like a small crater. That central dip may scab over and bleed, then seem to heal, then bleed again. This cycle of scabbing and bleeding without fully resolving is a strong signal. You might also notice tiny blood vessels visible on the surface. On darker skin tones, basal cell carcinoma can appear brown or black rather than pink, which sometimes leads to confusion with a mole.
Squamous Cell Carcinoma
Squamous cell carcinoma tends to look rougher and more irritated than basal cell. Common appearances include a firm bump (nodule) on the skin, a flat sore topped with a scaly crust, or a wart-like raised growth. The color varies with skin tone: it can look pink, red, brown, or black.
Pay attention to your lips, too. A rough, scaly patch on the lip that develops into an open sore can be squamous cell carcinoma. These cancers also show up inside the mouth as sores or rough patches, and occasionally on the genitals or anus as raised, wartlike growths. A new sore or bump that develops on top of an old scar is another warning sign specific to this type.
How It Differs From Precancerous Spots
Squamous cell carcinoma often starts as a precancerous rough patch called an actinic keratosis. Telling the two apart by eye alone is difficult because they exist along a spectrum. But there are clues. Squamous cell carcinomas are typically thicker (averaging about 1.4 mm in height compared to 0.5 mm for precancerous spots) and slightly wider. They’re also more likely to be tender to the touch, to bleed, and to noticeably change in size. If a rough patch you’ve been watching suddenly grows, starts bleeding, or becomes sore, that shift matters.
Melanoma
Melanoma is less common than basal or squamous cell carcinoma but far more dangerous. The widely used ABCDE guide gives you five features to watch for in any mole or pigmented spot:
- Asymmetry: One half of the spot doesn’t match the other.
- Border: The edges are ragged, notched, or blurred rather than smooth. Pigment may seem to bleed into the surrounding skin.
- Color: Multiple shades are present, including mixtures of brown, black, tan, white, gray, red, pink, or blue.
- Diameter: The spot is larger than about 6 millimeters (roughly the size of a pencil eraser), though melanomas can start smaller.
- Evolving: The mole has visibly changed in size, shape, or color over recent weeks or months.
Not every melanoma checks all five boxes, especially early on. The “evolving” criterion is sometimes the most useful on its own, because any mole that is actively changing deserves attention regardless of its other features.
The Ugly Duckling Sign
Beyond the ABCDE checklist, there’s a simpler instinct worth trusting. Most of your moles tend to resemble one another in color, size, and shape. If one mole stands out as clearly different from the rest, that “ugly duckling” is worth showing to a dermatologist. Studies have found this approach is a sensitive way to spot melanoma, even for people without medical training. You’re essentially looking for the one that doesn’t belong.
Melanoma That Doesn’t Look Dark
About 5 percent of melanomas are amelanotic, meaning they lack the dark pigment most people associate with the disease. Instead, they appear as a pink, red, or skin-colored bump or patch. Because they don’t look like a typical dark mole, they’re frequently mistaken for a pimple, bug bite, or harmless irritation. This confusion means amelanotic melanomas are often diagnosed at a later, more advanced stage. If you have a pink or reddish spot that persists, grows, or doesn’t respond the way a normal blemish would, take it seriously.
Skin Cancer Under the Nails
Melanoma can develop beneath a fingernail or toenail, where it typically appears as a dark vertical streak running from the base of the nail to the tip. Think of it as a line drawn with a brown or black marker. The streak usually starts narrow, often less than 3 millimeters wide, but may widen over time, especially at the base near the cuticle. The color can be uneven, with varying shades of blackish brown.
Over time, the line can multiply into additional streaks or spread to cover more of the nail. The nail itself may split, crack, develop dents, or become deformed. In some cases, there’s no discoloration at all. Instead, a small irregularly shaped growth develops and lifts the nail away from the nail bed. This type, called subungual melanoma, is the most common form of melanoma in people with darker skin tones.
Skin Cancer on Darker Skin
Skin cancer looks and behaves differently depending on skin tone, and many of the common descriptions (pink bumps, red patches) are based on how cancer appears on lighter skin. In people with darker skin, the most common melanoma type is acral lentiginous melanoma. It shows up in places that get less sun exposure: the palms of the hands, the soles of the feet, and under the nails.
On your palms or soles, it can look like a dark, irregular patch that may be mistaken for a bruise or stain. Under the nails, it appears as the dark band described above. Checking these areas regularly is important because skin cancer in these locations is easy to overlook. If you notice a dark band on a nail, especially one that’s widening or spreading to the surrounding skin, that warrants a closer look from a professional.
Merkel Cell Carcinoma
Merkel cell carcinoma is rare but aggressive. It typically appears as a firm, painless, red or pink nodule on sun-exposed skin, most often in people over 50 with fair skin. The combination of features that sets it apart can be remembered with the acronym AEIOU: asymptomatic (not tender), expanding rapidly, immune suppression, older than 50, and ultraviolet-exposed skin.
The key paradox of this cancer is that it grows fast but doesn’t hurt. In a study of 195 patients, 88 percent of Merkel cell tumors were painless despite the fact that 63 percent had grown rapidly in the prior three months. A red or pink bump that’s getting bigger quickly yet causes no pain or tenderness is the combination that should raise concern.
The Two-Week Rule
With so many possible appearances, the most practical guideline is straightforward: any new or changing spot on your skin that persists for two weeks or more deserves a professional evaluation. This includes sores that scab but never fully heal, bumps that appeared recently and aren’t going away, moles that have shifted in color or size, and any persistent patch that bleeds, itches, or crusts without explanation. Skin cancer is highly treatable when caught early, and two weeks is enough time to distinguish a temporary irritation from something that needs a biopsy.